Determination of Organic Acids in Beer After Extraction with an Anion-Exchange Resin

The organic acids in beer were recovered with an anion-exchange resin and then were converted to their methyl esters by treatment of the resin with boron trifluoride-methanol. More than 50 compounds recognizable as methyl esters were found by mass spectrometric analysis of the extract from 50 ml of beer. Satisfactory calibration lines were obtained for a number of volatile and nonvolatile acids via the method of standard additions and gas chromatographic analysis. The method is limited by the overlap of some methyl ester peaks in the gas chromatogram.